Once you complete the signup process, you are able to search for jobs and startups you would like to apply to. You can then apply to them with a single click.
Startups can also show interest in your profile. You will receive an email if a startup has shown interest to you. If you reciprocate that interest, you can then start a conversation with the company.
Quick tip: the more preferences and information you include on your profile, the higher the chance that you will be contacted by a startup!